This invention relates to a form system for ceiling formworks which comprises shores and form boards which are supported by these shores thus that their edges contact one abother to form a continuous uninterrupted forming surface.
At present, formworks for ceilings are erected such that form bearing members which may be pre-fabricated, or crossbeam timbers which are cut to size on site, are positioned on steel tube supports or shores which have been adjusted to a specific length. Depending on the load to be expected of the concrete forming the ceiling, other cross-girders or pieces of wood are positioned transversely, and the form boards or plates are positioned thereon. In the known form systems, pre-fabricated form boards are positioned between form bearers which are also prefabricated and are positioned on the steel tube supports, so that the form boards and the form bearers provide a continuous forming surface.
A disadvantage of these known ceiling formwork systems is the fact that they must be adapted as regards their structure and the material of which they are made to the respective strains, i.e. where there are changes in the constructional dimensions, such as in the ceiling thickness or in the height of the room, the dimensions of the cross-girders and the form boards vary, caused by the necessary changes in the mutual spacings of the steel tube supports. This in turn, necessitates keeping a correspondingly large stock which has a considerable effect on the investment cost involved. The comprehensive stock needed leads to an uneconomic stock utilization factor. Furthermore, keeping a stock which is appropriate to all cases of use necessitates a large number of individual parts.
As ceilings are positioned above the floor or ground at a height which is greater than the human reach, various people are required for erecting these known ceiling formworks, namely workmen to position the shores, workmen to move the form bearing members from auxiliary platforms and/or ladders, and workmen to work on the form surface in order to position the form boards from above into the form bearing members.
Thus, high assembly costs and extra costs, which cannot be calculated in advance, for auxiliary frames and for the erection thereof are added to the high investment costs.